1. Field of the Invention
The present invention relates to semiconductor fabrication apparatus and, more particularly, to exhaust systems for semiconductor fabrication apparatus. Still more particularly, the present invention relates to exhaust apparatus used in a semiconductor process for substantially reducing the damage caused by reacted gas from wafers.
2. Background Art
FIG. 1 shows a schematic diagram illustrative of a conventional machine 11 used for performing a semiconductor process. This exemplary machine is used to perform etching processes on semiconductor wafers. The semiconductor processing machine 11 is generally located in a clean room to help maintain a high yield of the process. A cassette of wafers 10 is loaded into an etch chamber 12 by a load mechanism 14. After the wafers are processed in the chamber 12, the wafers are unloaded by an unloaded mechanism 16. The load and unload mechanisms 14 and 16 are housed within a cabinet or chassis 13, along with other structures and units (such as electronic components and an electrical/mechanical system to move the cassette of wafers between the load and unload mechanisms and chamber) of the semiconductor processing machine 11.
While the wafers 10 are in the load mechanism 14 and the unload mechanism 16, gas 18 such as Cl.sub.2 and/or HBr typically is dissipated out of the wafers. Therefore, the semiconductor processing machine 11 has a conventional exhaust system to remove the gas 18 from the load and unload mechanisms 14 and 16. More specifically, the load mechanism 14 and the unload mechanism 16 are equipped with fans 17 to move the gas 18 out of the load mechanism 14 and the unload mechanism 16 into the interior of the chassis 13 of the machine 11. The fans 17 thereby cause a relatively high pressure within the chassis 13 relative to the exterior of the chassis. Because of this pressure difference, the gas 18 blown by the fans 17 into the chassis interior flows through an exhaust opening 19 in a side panel of the chassis 13, where the gas 18 is finally collected by an external exhaust treatment system (not shown), such as an exhaust scrubber. In addition, this pressure difference also causes an air flow through the chassis interior that carries the heat generated by the electrical/mechanical system and other electronic components (i.e., waste heat) out the exhaust opening 19.
The inventor of the present invention has observed that in these conventional systems, the interior surface of the chassis 13 and other exposed structures within the chassis interior (e.g., gas lines, printed circuit cards, cables, etc.) located within the chassis can be damaged due to the corrosive nature of the gas 18. More specifically, the gas 18, in moving from the load and unload mechanisms 14 and 16, tend to cause any exposed structures within the chassis 13 to rust or corrode. The operation and reliability of the electrical/mechanical systems (not shown) housed within the chassis 13 are also detrimentally influenced by the gas 18. Moreover, maintenance operators or technicians are likely to be exposed to the gas 18 while performing maintenance duties. In general, exposure to the gas 18 can be hazardous to human health. Still further, if the fans 17 are out of order, a portion of the gas 18 will tend to flow upwards and escape out of the load and unload mechanisms 14 and 16, thereby contaminating the clean room environment. In addition, this escaping gas tends to interfere with the normal air flow 15 in the clean room, resulting in an unacceptable environment for the semiconductor manufacturing process.